Pneumatic tires are conventionally of a toroidal shape which defines a cavity which is substantially enclosed by the tire and the closure is conventionally completed by mounting the tire on an intended rigid rim. The tire conventionally has a rubber innerliner which is actually an exposed surface of the tire cavity. Such pneumatic tire configurations are conventional as would be understood by one having skill in such art.
Pneumatic tires usually rely upon air pressure to maintain their shape and associated performance during service conditions, although some pneumatic tires may be designed to hold their shape and provide representative performance, at least for limited times, even though they may have lost or are not able to maintain their internal air pressure for various reasons. For the purpose of the description of this invention, such tires are considered herein to be pneumatic tires even though they might be designed to run without an internal air pressure for limited periods of time.
For various applications, it may be desirable to provide a pneumatic rubber tire with a sensing device on or within its inner surface which has a capability of electronically receiving power generated from an electromagnetic wave generating source outside the tire and transmitting various data relating to the tire such as, for example, its internal air pressure relative to an external transmitting and receiving device.
It may be desirable to provide such a tire with a suitable antenna as an actual part of the tire for both receiving various electromagnetic signals from an exterior source and for transmitting various electromagnetic signals from within the tire to an external receiving device.
It may also be desirable to utilize a flexible rubber composition with relatively low electrical resistance to both physically and electrically connect various electrical devices such as, for example, connecting a microprocessing device or chip, which is positioned on or within an inner surface of the tire to an electrical wire.
In the case of one electrically-conductive element such as, for example, an electrically-conductive metal wire, it is envisioned herein that the rubber composition of this invention may be used to electrically connect at least two portions of the same element in the case of one element or of a multiplicity of elements in the case of two or more elements.
Accordingly, it is envisioned that a suitably electrically-conductive rubber composition would be desirable for connecting said microprocessing device to at least one additional non-rubber, electrically-conductive element such as, for example, a wire or other metallic electrical element or conductor, especially where considerable flexing at the point of connecting the electrical conductor to the microprocessor, or other electrical device or element, is concerned.
It is also envisioned, in one aspect, that such electrically-conductive rubber composition may be in a form of an aforesaid antenna as an annular strip of rubber positioned on or in a tire innerliner.
Such an antenna will necessarily have a suitable electrical-conductivity for its purpose and have a suitable elastomeric properties for compatibility with the inner rubber surface of the tire itself.
An example of use of an electrically-conductive rubber on an inner surface of a tire may be found, for example, in U.S. Pat. No. 5,743,973.
An important requirement for such electrically-conductive rubber composition is not only that it be relatively electrically conductive but, also, that it have physical properties suitable for inclusion within a tire component so that the electrical conductivity be maintained over time.
For the description of this invention, the term "phr" refers to "parts by weight of a designated ingredient in a rubber composition per 100 parts by weight of rubber".
The terms "rubber" and "elastomer" are considered herein to be interchangeable unless otherwise indicated and, for the purposes of this description, a liquid rubber, which may be a diene hydrocarbon-based liquid rubber or an isobutylene-based liquid rubber, even though it is a liquid, it is referred to herein as a "rubber" which, upon curing, has rubbery properties. Non-liquid rubbers may be referred to herein as "solid rubbers".
The terms "rubber compound" and "rubber composition", or "elastomer composition", where used, are considered herein to be interchangeable unless otherwise indicated.